Here Fishy, Fishy

Jami Sloan, a recent graduate of the Integrated Biosciences master's degree program, did extensive research on carp and their response to sound.

Allen Mensinger, UMD biology professor, currently investigates fish sensory physiology with four graduate students and four undergraduate students in the lab.

Here carp are seen responding to an audible tone.

There is no question the common carp are a threat to Minnesota’s environment, so UMD is training them.

Scientists and natural resources professionals have experimented with various methods to stop the spread of the common carp (Cyprinus carpio). Encouraging people to eat them hasn’t worked, at least in the U.S. Using nets and introducing species-specific viruses haven’t worked. Poisoning harms the environment, so it isn't an option. Now, new research from the Department of Biology at the University of Minnesota Duluth (UMD) promises to reduce this dangerous threat. Jami Sloan, a recent graduate of the Integrated Biosciences master's degree program, and Allen Mensinger, biology professor, are training carp.

There is a long history of training animals through acoustic conditioning. "When animals, even fish, associate food with a particular sound, they learn to expect food when the sound is heard," said Sloan. "We used a 400 Hz sound signal because it is within the 300-1,000 Hz hearing range of carp."

The UMD experiment played a pure tone for the carp. It was similar to the sound when a phone is off the hook or when a T.V. station goes off the air. The carp quickly made the association between the tone and food, and they retained the behavior. Within five months after Mensinger and Sloan stopped providing food along with the tone, the carp continued to respond.

Mensinger is pleased with the success of the experiment, “We now know acoustical conditioning may be used as a management strategy for trapping and removing wild carp within a lake system.”

Acoustical conditioning presents new insight into the brains of this fish. There is a possibility to train millions of wild carp to eliminate the growing population of this havoc-wreaking fish.

About Invasive Carp

Sloan worked with the common carp (Cyprinus carpio), however Asian silver carp may be affected by sound in similar ways. Both fish are freshwater natives of Eurasia and are known as some of the world’s most invasive species.

Common carp are unable to completely digest their food and that creates immense amounts of algae. Not only does their waste harm the environment, but it also impairs the native fish found in the Great Lakes and smaller lakes. Common carp are known for destroying the nests of native fish, eating their eggs, and consuming submerged vegetation that ducks depend on.

Asian silver carp, or "flying carp," pose an even greater threat to U.S. rivers and the Great Lakes because of their size, rapid reproduction, and their ability to consume large amounts of food. They are huge, growing to 100 pounds or more.

The Asian silver carp have steadily made their way up north from southern states, becoming the most abundant species in some areas of the Mississippi River, out-competing native fish, and causing severe hardship to the people who fish the river. They currently have been found only 40 miles from Lake Michigan. They already compete for food with the valuable sport and commercial fish in rivers. If they enter the Great Lakes system, they will likely become the dominant species in those waters.

The equipment Sloan used on her work with common carp is being employed with flying carp this month (September, 2013) at the USGS facility near the Mississippi river in La Crosse, Wisconsin. UMD graduate students are conducting experiments with a slightly different focus. “With flying carp we are experimenting with bioacoustics to repel the carp," said Mensinger. "Jami's project with the common carp used acoustical conditioning it to bring them in.”

From Experimentation to Application

Allen Mensinger and his undergraduate and graduate students are sharing their research in an effort to provide officials and organizations the knowledge to combat the growing populations of these invasive species.

The word is getting out about the UMD studies. “I presented our project to the American Fishery Society in 2010" said Sloan. "I briefly spoke with some DNR members, but no one has taken the next step.” She has a plan. "We could tag wild carp and set-up the sound equipment in a small lake system. By tracking the fish we could get an idea if the fish are conditioned to the sound signal. If successful, the fish could then be trapped and removed."

Mensinger is ready for larger projects as well. “We know there has been interest from the DNR," he said. "With secure funding it would be great to move from pool studies to field studies."